Overload-indicating apparatus for transformers



Dec, 30.- 1924 v T. D. ADAIR, JR OVER'LAD INDICATINQ APPARATUS-.FORTRANSFO RMERS gr. ww.

Patented Der, Eil, i924.

narran stares ears THOMAS DONALD ADA1R,`JR., OF DORCHESTER,MASSACHUSETTS, ASSIGNiOR, BY

MESNE ASSTGNMENTS, TO LEONARD L.

ELDER', `GF BRQOKLTNE, MASSACHUSETTS,

" .AND DAVIS S. BOYDEN, 0F BOSTON, MASSACHUSETTS.

DVERLOAD-TNDICATING ATDPARATUS FOR TRANSFQRMERS.

Application filed August 15, 1922. Serial No. 582,057.

inent-s in @verload-nclicating Apparatus for Transformers; and I dohereby declare the following to be a full, clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit 'appertains to make and use the same.

The present invention relates to an improvement in overload indicatingapparatus for transformers, and more particularly to semaphores for usein connection'with such apparatus.

In the transformer disclosed in the application iiled by T. DonaldAdair, J r., April 8, 1921, Serial No.4 459,574, the semaphore wasenclosed within a semaphore box having a window in one side. Withsuchconstruction whenl the semaphore drops it is exhibited at thewindow. ln practice, in order to render the semaphore visible anddistinguishable, it is painted white. Upon the occurrence of transformeroverload the white Lseniaphore'was exposed to view by the droppingbehindA the window. The box, however, was made of metal and the insidewas illuminated only by such light as could enter through the window,asia consequence jef which there was a mirror effect observed. The glassin cert-ain positions ofthe sun or clouds would reflect light to such anextent that the observer at a distance, as was necessary because thetransformers are usually mounted on poles, would be unable todistinguish the lightr reflected from the glass from the whitesemaphore. Y

lt was attempted to overcome this objection by the constructiondisclosed in Vthe applicationl of T. `Donald Adair, Jr., filed Octoberll, 1921, Serial No. 507,029, byproviding the box with two windows, oneat cach side, so that transmitted light might be availed of, that is tosay,`ligh t passing clear through the box, to Vindicate the fallling ofthe semaphore when it stood against a light background, and at thesametime it was provided that a white Vscreen covering part of the areabetween'thevtwo windows should be exposed by the dropping of thesemaphore for the purpose Vof rendering the signal visible-against adarli background. But the box in this case, as in the former, was madeof metal and excluded v.light more or less, and consequently7 in thisbox, as'in the former, the mirror effect was still encountered, andunder some condi.- tions it interfered with the visibility of thesignal.

The value of these semaphores is considerable even if the visibility ofthe signal Y is low, but with a high visibility the value of the signalismuch enchanced. To this end the present invention contemplates theproduction of a signal of high visibility, and consists in the semaphorehereinafter described and particularly defined in the claims.

In the accompanying` drawings illustrating the preferred form of theinvention, Fig. l is a vertical sectional elevation of the constructionofthe invention; Fio. 2 is a transverse sectional elevation; anc Fig. 3is a plan.

The illustrated embodiment of theinvention is described as follows: Theoverload indicating apparatus for transformers comprises a semaphore 19operated by mechanism responsive to the overload conditions of thetransformer coils, comprising a heat responsive element, such as a coilor spiral like that described in said applications, or of any suitableform, which is connected to a rotatable spindle 25 journaled at itsupper end in a cross bar 27 within thesemaphore box 28, mounted on theupper end of a depending boss 29, having a threaded portion 30 adaptedto be screwed into a hole in the cover of the transformer. Variations inthe temperature of the coils in tlv,` transformer operate through theexpansion or contraction of the heat responsive coil or spiral to causerotation of the rotatable spindle 25. The semaphore box is made of onepiece of glass. It is provided with bail groove projections 3l von itstop which receive the horizontal portion of the `bail 32 which has twoarms extending downward at the sides of the box which enter two slots 33in the base plate 34 and receive on their ends the lmurled nuts 35. Arubber washer 36 is interposed between the base plate 34C and the loweredge of the boX 428. .By screwing upthe nuts jon 4the bail the box isclamped tightly against the base plate, and the entrance of water or airthroughrsuch opening is prevented. yThe :semaphore 19 is suplrbortedjtoslideon veri rotated to bring the notch under thepspring,

as in the construction ofI said applications. rlfhisspring 4lispermitted to all'by two steps, beingl provided with a shoulderl43 which,when'the semaphore is irst: permitted Y .to fall, catches 'on the disk42 and holds thesemaphore in a position vhalffwaybetweenm its t'p,4 andbottom positions. This :construction is4 like that illustrated in theDavis S. Bot'vden'afplication tiled June 16,*V

. Y 1921, Serial No. 47 8,205.

l The semaphore `is provided witha re-set- Lting device consisting ont,a level-'44"pivoted at `45, adapted to be engaged on itsnnder side bythe refsettingpin 46. The 1re-setting pin projects through the bottomofthe -base of the, device and is covered byua 'cap 4 7 which has a holeextending downward in its center for a, distance to receive thelo-wer llend ot'theLre-setting pin and which has a screw-threaded. shankladapted to bereceived lin ascrewthreaded Vhole m the ibase, through.which the re-setting pin, much smaller ,in size, projects. A rubberwasher the closure to be made tight. By means of the vwasher under thebox and the washer .underl the resettingjpin cap the 'apparatus is madehermetically tight, and this prevents the entrance and 'egress'of airandof moisture,.an'd maintains the condition ollthe ap- .paratus tree fromexposure to the mfiuenco o'litheweather and insects.

The upper'ends of the two rods 40 ,are receivedin two holes in the topVpiece49 of a background 'against which' this device may? Eiframe, whichasl seen in 2,`"co1i'sists ot' a j flat base 27 and two verticalsupports 50 (see Fig. 1,),fupon the -upper ends of which the horizontaltop piece 49 is formed. This fralnejis secured to-the two postsV 5l and52 (fof which thepost 5l carries the resetting lever) which are formedon the base plate f vIrre'spective of the vsurroundings or thebeviewed,` the full light which is enabld to illuminate the wholeapparatus by reason of the box being made of glass, ,substantiallycompletely obviates anyimirror liect on the glass.V yWhen 1t 1s viewed.against a darkV background the semaphore cuts otthat dark bacllground.`W Then viewed against a light background, the i a dark'objectagain'stit. The Kresultfis that the SemapbereisClient.high Visibility byreason of the employment ot' aglass vbox:

,or ,c,over. .The ideal condition Would, ot'V course, be that in whichno Ycover at all was employed, but such cond1t1on,1sas.n matter ot`lpractice, impossible because weather Vcmdition's and the, liabilitypofinjiiry byianimais. such asbirds, vsquirrels `andfinsects would Vbepresent, so fthat ,thejprsent coni. structionoffers .anY approximationtosuch ideal conditions.which,.secures a high de- `greener visibility-'lofthesemaphore,V

The use of thebail construction fnhold'ing the box on thebaserplateisfof greatlconvjenf ience .in theuse'of the.device.becausefitienables the inspector to remove thecoverentirely.andto have'full and `tree ,accessft'o the apparatus for thepfurposeocleaning itJsjfor removing any rust,fdust,.fcorr0sion o r other ef'presents impediments. to.. its goocl-f.0pe1-ation,and Y quickly torestore it to itsl originalti'ghtconydition'attach cleaning operation.,1

V-The feature of ^he initicallyl-,sealing the box is one [whichcontributes greatly to 'the life and durability ofithe instrument be-Vcause itgprevents the` corrosion and ,deterio- Vration incident totheohangefof the Vair Y oontent of the 'box due tothe expansion andcontraction such air resulting j from changes of temperature, A

:n will .befobseifved that itis, essntialjthat Vthe front vandback wallsof thecasingjwshall .be tramsparenty and Athatfthe semaphoreplate `l9shall nothonly be substantiallyfopaque ,but` shall have substantialwidth, so that 48interposed` between'. the head of the cap x .4 7 andthe bottom of thebase plate enables whenitfis in itsfjup' posit-ionYwill, so to Speak, block ol-ajrlarge part ofthe 'top anel Ot' vthe,casing, g1 eavingtheflower haia or panel substantially transparenttonenable the light rays tofpassclearthrough the 'cas ing. lVhentheopaque semaphore-plate is down, thenthe conditions are reversed, the

yligljit `passing 'clear through the'top zone or panel of the casing,u l,Ijn':thiswvayjthe'panel blocked ofi; bythev opaqueplate will, by comf parison with the "transparent 7'sectimI oaf` the basing, be, readilyobservable Iat consideru indicating apparatus V 'for transformershavingf in"A combination, a

semaphore, a heat sensitive elemengjconnections between' the semaphfle.`and` the 'heat Y sensitive Y element 'perm ittingrV thelsemaphore tto'`drop",upon theindication' et, ritic'al; tem perature by the heatsensitive eleV Vent', a box Yl'or covering the semaphore, a Wire bailextending over the box, and means for securing it to the base plate tohold the box in place thereon.

2. Overload indicating` apparatus :for transformers comprising a heatsensitive element, a semaphore, connections between the heat sensitiveelement and the semaphore acting to drop the semaphore upon theattainment of a critical temperature at the heat sensitive element, .abase plate for supporting the semaphore, a box for covering thesemaphore, means for packing the joint between the box and the baseplate, a re-setting device having a portion extending through the baseplate, and a cap for coverino' the rea-setting device, said box and aphermetically closing access to the box.

3. An overload indicating apparatus for transformers having, incombination, a box for enclosing the indicating apparatus, the Walls ofthis box being transparent, said indicating apparatus embodying alight-obstructing semaphore-plate of substantial Width adapted to beheld in the upper part of the casing or in the lower part thereof, sothat in either position it Will render the casing nontransparentl atthat point and thus indicate at a glance under all light conditionsWhether the semaphore-plate be up or down.

T. DONALD ADAIR, JR.

